Typically, most conventional firearms have been adapted for specific tasks and generally are limited to use with specific calibers and/or types of ammunition. However, demand is increasing for firearms that can be modified to fire different types of ammunition, and/or can be reconfigured for different environments and uses. For example, in military applications today, the environments in which soldiers are forced to fight are changing such that they can be in open desert and then move into close quarter's battle in a more urban area within the matter of a few hours. At the same time, their weapons needs can further change, i.e., they might be faced with need for a longer range, sniping weapon or alternatively with needs for a more standard infantry rifle depending on the environment or situation. Carrying multiple different firearms is, however, impractical as adding undue weight and bulk to soldiers' packs and gear. Additionally, for more specialized uses, such as for sniping and other tactical situations, the weapon must be configurable as needed to fit the shooter's particular needs and/or use in a particular combat situation.